Chain saws are typically provided with a guide bar which has a longitudinal slit defined along its edge, and have an endless chain engaged with the longitudinal slit of the guide bar. The endless chain is driven by a driving sprocket provided at one end of the guide bar. The chain is usually comprised of a plurality of chain links which include outwardly oriented sawing teeth, and inwardly oriented guiding projections, or tabs. The tabs engage the slit, and can also be in mesh with the driving sprocket for driving the chain. Sliding of the tabs within the slit and engagement thereof with the sprocket results in friction.
To reduce the friction between the endless chain and the guide bar, chain saws of forestry equipment are typically provided with at least one oil conduit through the body of the guide bar and having an outlet located in the slit. Oil is fed through the oil conduit, and is received by the guiding tabs of the chain. The guiding tabs of the chain spread the oil along the slit as they travel therein.
Although such methods of lubricating chain saws with oil have been used for decades, and have been satisfactory to a certain degree, they are met with several drawbacks. For instance, the speed at which chain saws of forestry equipment such as tree fellers or saw mills are operated generates a relatively high level of centrifugal force which drives the oil to be evacuated outwardly from the chain links. As a result, a relatively high volume of oil is typically consumed. For instance, a tree feller can consume close to 2 500 liters of chain saw oil per year.
In addition to cost considerations, disposing of the oil can have environmental consequences. In the case of tree fellers, the oil is typically released onto the forest ground.
There is therefore a need to reduce the amount of lubricant consumed by chain saws of forestry equipment. There is also a need that chain saw lubrication be done in a more environmentally-friendly manner.